通过研究中国西部1970年以来7次MS≥6.5破坏性大地震震后24h内余震能量场的空间变化，分析和判定主震破裂的大致范围，从中得出可能的宏观震中位置，进而为大地震的应急救援提供参考。本文以汶川地震为例说明最小完整性震级的确定、能量场的计算方法及其分布图的绘制以及宏观震中的确定等，并对7次地震震后各个时段的估计震中和实际的宏观震中进行比较和分析。研究结果显示： ①利用破坏性大地震震后24h内不同时段由余震能量场分布得到的宏观震中，可有效缩小用微观震中评估烈度产生的偏差； ②震后2、4、6、12、24h等5个时段的估计震中能够作为烈度快速判定的修正因子满足震后快速响应的时效性要求，且震后24h的估计震中效果最好。

The deviation of micro-epicenter and macro-epicenter is an urgent task in the rapid judgment of earthquake intensity. This paper aims at studying the main area of earthquake rupture and mark the possible position of macro-epicenter through the research on aftershock energy field distribution within 24 hours after 7 strong earthquakes with MS6.5, so as to provide reference for emergency rescue. This paper takes the Wenchuan earthquake as a case study to illustrate how to make sure the magnitude of completeness, how to render the distribution chart of energy field and the calculation method of energy field, as well as how to determine the macro-epicenter. This paper then compares the estimated epicenter with the actual epicenter at each period of the 7 earthquakes and comes to the conclusion that：(1)At each period of the 24 hours after the catastropy, the macro-epicenter referred from aftershock energy field distribution could reduce the deviation referred from the estimates epicenter of micro-epicenter. (2)Estimated epicenter at the periods of 2, 4, 6, 12, and 24 hours after the quake could act as the correction factor of rapid judgment of earthquake intensity with the excellent effect in the period of 24 hours after the quake.

地震科技星火计划项目(XH14056)、“十二?五”国家科技支撑计划项目(2012BAK15B06-02)共同资助